#!/bin/sh
# giua 2 bieu thuc so sanh x=y la ko dc phai de la x = y (co khoang trang)
echo input
read myvar
if [ "$myvar" = "a" ]
 then
   echo "$myvar = a"
elif [ "$myvar" = "b" ]
  then
   echo "$myvar = b"
else
   echo "$myvar ??"
fi
exit 0